Conventionally, a system that displays a branch point diagram, which shows a simplified shape of a branch point when the vehicle approaches the branch point, is disclosed in Japanese patent application Laid-Open No. 2008-45925 ('925). Such a branch point diagram displayed in the above application includes a shape of the branch point (i.e., a crossroad, a Y shape road, and the like) as well as road names and/or district names to which a certain branch leads to (i.e., municipality names of towns and cities to which a certain branch leads vehicles to).
However, data for displaying such diagram including various figures, district names along with a branch shape, and other information may increase the data size. Therefore, data delivery of such diagram data from a delivery server may result in an increase of communication cost and time. Further, such a large data size may consume a data memory of a navigation apparatus or a terminal in the vehicle if it is pre-stored in the terminal. As a result, the display of the branch point diagram may take time and may not be shown in a timely manner.